How Can I Understand Common Wifi Internet Issues

Understanding the Functioning of Internet Addressing

When you connect to the Internet, you are assigned a Public IPv4 address such as 35.41.3.69 or an IPv6 address like 2000:328b:5a2f:59c4:f43d:a297:1102:956a. You can verify this information by visiting https://test-ipv6.com/. However, sharing or using these addresses, as well as MAC addresses like 96:f9:97:77:20:5a, can be prone to errors and becomes intricate. Furthermore, it does not provide any historical data, especially when previous issues occurred.

Navigating the Internet

When visiting a website such as https://padberg-bosco.net, the first step is to access a DNS server to convert the host portion (padberg-bosco) along with the Top Level Domain (net) of the URL to an IP address like 162.92.27.39. Your computer and browser include its type with every web request, for example:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/7046A194A

Significance of Default Gateways

You typically receive a default gateway automatically as a DHCP-configured address, such as 172.31.118.5 (usually ending in .1 or .254 depending on the scope size). This is where your computer sends all its traffic to be routed onwards. For IPv6, you can find detailed information on how-to-fix-ipv6-connectivity/ or check on a Mac or Linux using:

IPv4 Routes and the Host IPv4 Route Table (inc. VPN)

netstat -rn -f inet | egrep -i "default|0/1|128.0/1"

0/1      172.18.12.193  UGScg  utun3
default  172.31.118.5    UGScg  en0
128.0/1  172.18.12.193  UGSc   utun3

Note: We are not just looking for the default but also for any VPN that overrides the public v4 address space.

IPv6 Routes and the Host IPv6 Route Table (inc. VPN)

netstat -rn -f inet6 | egrep -i "default|2000::/3"

If you have IPv6 active the above should return at least one route (as per below) via a known interface such as “en0 " on a Mac.

default   fe80:8b97:6da4:31a:ff11%en0  UGcg   en0
default   fe80::%utun0                   UGcIg  utun0
default   fe80::%utun1                   UGcIg  utun1
default   fe80::%utun2                   UGcIg  utun2
2000::/3  utun3                          USc    utun3

Note: We are not just looking for the default but also for any VPN that overrides the public v6 address space.

Debugging DHCP for both IPv4 and IPv6

To get a look at the low level DHCP configuration (Mac/Linux):

ipconfig getpacket en0

...
domain_name_server (ip_mult): {57.239.21.142, 88.55.32.143}
end (none):
...

So, in the above we are not getting IPv6 DNS servers from the DHCPv4 reply but…

ipconfig getv6packet en0

DHCPv6 REPLY (7) Transaction ID 0x80940b Length 76
Options[4] = {
  CLIENTID (1) Length 14: DUID LLT HW 1 Time 668691856 Addr 96:f9:97:77:20:5a
  DNS_SERVERS (23) Length 32: 2606:4700:4700::1111, 2001:4860:4860::8844
  DOMAIN_LIST (24) Length 0:  Invalid
  SERVERID (2) Length 10: DUID LL HW 1 Addr 98:4b:23:50:6c:9a
}

Resolving Issues with Wired and Wireless Connections

When transferring data to your router, you may be utilizing either a wired or wireless (Wi-Fi) medium at the physical and data layer.

Troubleshooting Tips for Apple macOS / OSX

Irrespective of the version of OSX/macOS you are using, whether it’s 10.13.9, 11.4.3, or 12.2.1, there are various tools available for fixing issues. However, these manual actions and scripts do not provide a set of correlated values over time. For this reason, automated remote troubleshooting becomes essential, particularly for teams engaging in remote work and Work From Anywhere (WFA).

Utilizing Built-in Scripts for Assistance

One useful tool on OSX/macOS is sudo wdutil info, which provides a dump of current wireless settings to the CLI and can be configured to generate specific logs for troubleshooting. Additionally, the sysdiagnose tool can be used to generate a wide range of logs, although many of them are only applicable at a specific point in time in relation to wireless, similar to wdutil.

By running sudo nohup /usr/bin/sysdiagnose -u & in the background, logs will be written to /var/tmp/<blah>.tar.gz. Alternatively, for an interactive run (even though there is minimal interaction), you can execute
sudo /usr/bin/sysdiagnose, which will display a privacy warning. If not run in the background, it should open Finder in the correct location, or you can navigate to /var/tmp using Finder with Cmd+Shift+G. However, beware of the file sizes, which are around 300MB more or less.

Possibly Helpful Videos

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Table 1.0 - Video Help